Friday 6 May 2011 12.47 EDT
First published on Friday 6 May 2011 12.47 EDT

Revelations that American spies monitored Osama bin Laden from a safehouse for months before last Sunday's special forces raid have caused further consternation inside Pakistan, where the military is already fighting angry criticism.

CIA agents sequestered in a rented house conducted extensive surveillance on Bin Laden's hideout using an arsenal of high-tech surveillance equipment including telephoto lenses, eavesdropping equipment and radars to detect possible escape tunnels, US media reported on Friday .

It was the CIA's most sensitive operation in a decade, so intense that the spy agency had to seek tens of millions of dollars in emergency funding last autumn.

The news came as a further embarrassment to Pakistan's beleaguered military, which is being criticised for failing to locate Bin Laden in Abbottabad, a garrison town that is home to Pakistan's top military academy.

Now it seems that Inter-Services Intelligence also failed to detect a CIA team that, like Bin Laden, was operating under its nose. "It increases their discomfort and makes them look even more incompetent," said Najam Sethi, a prominent analyst.

The CIA set up its Abbottabad safehouse sometime after August after identifying the compound where bin Laden's courier, a man identified by the US as Sheikh Abu Ahmed al-Kuwaiti, was living. A US team rented near the hideout with a mission to "find and fix" Bin Laden, according to the Washington Post.

The spies took pains to avoid detection by their Pakistani counterparts – raising further questions for Pakistan about how easily the CIA can operate in their country. "They have the run of the place, which is why the ISI is so upset," said Sethi.

Revelation of the operation casts new light on American handling of the furore surrounding Raymond Davis, an American spy who shot two Pakistanis in Lahore last January. It is now clear that while the CIA was battling with its largest public controversy in Pakistan for years, it was also engaged in its most sensitive covert operation.

Michael Scheuer, a former head of the Bin Laden team at the CIA, said: "We are very good at what we do. Abbottabad is a challenge but it's not like Moscow or Prague where we ran observation posts for years and years. It's part of our MO [modus operandi]."

Scheuer said that since 2001 the CIA has made a concerted effort to recruit Pakistani-Americans, or Americans whose physical features help them resemble locals from Middle Eastern and South Asian countries, enabling them to blend in.

The agency has also recruited ethnic Pashtuns to work in the borderlands tracking al-Qaida and Taliban suspects and acquiring targets for the controversial drone strikes, according to a former CIA officer who has worked in Pakistan.

Some of the Pashtuns are directly employed by the CIA, he said, while others are "cut-outs" – spies hired through a third party who are ignorant of the identity of their paymaster.

But it is unlikely non-Americans were involved in the Abbottabad operation, Scheuer said. "I doubt they were local nationals. This is something we clearly want to do ourselves," he said.

But despite the intense surveillance effort the CIA was unable to obtain a photograph of Bin Laden or a recording of the voice of the mysterious man, presumed to be the al-Qaida leader, who lived on the second and third floors of the house.

The CIA is now analysing computer disks seized in the Navy Seals raid on Bin Laden's house for evidence of planned attacks on the US. But few Pakistanis believe it was really his house.

A YouGov poll conducted shortly after the attack found that 66% of Pakistanis think the person killed was not Bin Laden and 75% disapproved of the US raid. Opinion about Bin Laden himself was more evenly divided – 35% viewed him as a mass murderer of Muslims while 42% disagreed.

Meanwhile, the CIA resumed the hunt for the remainder of the al-Qaida leadership in Pakistan on Friday with its first drone strike since Bin Laden's death. A series of drone-fired missiles killed 15 people in a vehicle, a house and a restaurant in North Waziristan, according to reports.